title: Dynamic 1H NMR study around the carbon-carbon single bond and partial carbon-carbon double bond in the two particular phosphorus ylides and in an enaminoester.
abstract: Herein, a series of separate dynamic (1)H NMR effects are reported at different temperatures within a particular enaminoester involving a phenanthridine. These effects are attributed to restricted rotation around the two single bonds such as carbon-carbon (H(a)-C-<arrow curve left)>C-H(b)) and nitrogen-carbon (NC<arrow curve left)>COOCH(3)). Activation energies (E(a)) for these interconversion processes in their rotational isomers are equal to 20 and 20 ± 1 kJ mol(-1), respectively. In addition, three dynamic (1)H NMR effects are investigated at different temperatures for a particular phosphorus ylide involving a 2-indolinone around the carbon-carbon single bond (H-C-<arrow curve left)>C-PPh(3)) within the two Z- and E-rotational isomers and partial carbon-carbon double bond (OCH(3)-C=<arrow curve right)>C-PPh(3)). Activation energies (E(a)) for these interconversion processes in rotational isomers are equal to 53, 63 and 73 ± 1 kJ mol(-1) , respectively. This behavior was also observed for other phosphorus ylide containing 2-mercaptobenzoxazole around the carbon-carbon single bond and partial carbon-carbon double bond with their relevant activation energies containing 13, 10 and 75 ± 1 kJ mol(-1), respectively.
authors.affiliation: Department of Chemistry, Faculty of Sciences, The University of Sistan and Baluchestan, PO Box 98135-674, Zahedan, Iran. smhabibius@yahoo.com
authors.forename: Sayyed Mostafa
authors.initials: SM
authors.lastname: Habibi-Khorassani
authors.forename: Ali
authors.initials: A
authors.lastname: Ebrahimi
authors.forename: Malek Taher
authors.initials: MT
authors.lastname: Maghsoodlou
authors.forename: Sara
authors.initials: S
authors.lastname: Same-Salari
authors.forename: Shahin
authors.initials: S
authors.lastname: Nasiri
authors.forename: Hojjat
authors.initials: H
authors.lastname: Ghasempour